Diffuse reflectance fourier transform infrared spectroscopic study of the thermal degradation of barley protein

Abstract

Diffuse reflectance infrared spectroscopy was used to study isothermal degradation of crude barley protein, that was obtained as a side product of alcohol production. The isothermal temperatures used were in the range 50–150° C. Before analysis the protein fraction was dried either by lyophilization or spray drying. The drying method did not have a major effect on the subsequent isothermal degradation of the material. The main reactions observed in the spectra were oxidation indicated by the appearance of a broad composite carbonyl band and degradation of both proteins and starch. The reactions were visible already in the spectra taken at 70° C and there rates gradually increased as the temperature was raised to 150° C.